Hygiene, isolation and proper handling, essential to prevent the transmission of porcine reproductive and respiratory syndrome

A new study led by Agrotecnio and the University of Lleida (UdL) has characterized a highly virulent strain of porcine reproductive and respiratory syndrome virus (PRRSV) to assess its impact through two different routes of infection: intranasal, which mimics natural transmission, and intramuscular, which can occur due to poor farm management practices such as improper needle use. The findings reinforce the need to strengthen internal biosecurity measures, including strict hygiene protocols, isolation of sick or newly introduced animals and proper needle handling, to reduce the risk of PRRSV spread within and between farms. In 2020, a virulent PRRSV-1 strain, commonly known as ‘Rosalia’, was detected in northeastern Spain and spread rapidly. While official data on its impact remain limited, the research suggests that the strain may have contributed to a 5% increase in mortality during the rearing period in pigs between 2020 and 2022, indicating a substantial toll on the Spanish pig industry. The main objective of the study was to characterise the PRRSV-1 ‘Rosalia’ strain (Lleida 029_22) both in vivo and in vitro and to assess the effects of infection via two transmission routes under controlled experimental conditions. The work was carried out in collaboration with AM Animalia, the Grup de Sanejament Porcí (GSP) and the Centro de Investigaciones Biológicas Margarita Salas (CIB-CSIC). Key findings revealed that pigs infected intramuscularly, simulating management-related transmission like needle sharing, developed severe disease with 100% mortality. In contrast, pigs infected intranasally – a route mimicking natural respiratory exposure – showed milder clinical signs and a 30% mortality rate, but exhibited prolonged viral shedding, increasing the risk of transmission to other animals. Lead researchers Ana Stoian and Lorenzo Fraile commented: “we were not only able to replicate the clinical outcome observed on local farms affected by the PRRSV-1 ‘Rosalia’ strain, but also established an intranasal infection model that reflects the natural route of transmission. This provides a valuable platform for testing vaccines against this newly emerged and virulent strain.” A global threat to pig health and industry sustainability PRRS is one of the most economically devastating diseases in the pig industry worldwide. It causes high mortality in pigs, whether through natural exposure or farm-related practices, and results in a wide range of clinical manifestations, from reproductive failure in sows to severe respiratory illness in growing pigs, ultimately compromising productivity and animal welfare. PRRS is widely regarded as the costliest disease affecting pig production. In the United States, annual losses are estimated at $664 million, while in Germany, average losses reach €74,181 per farm per year. PRRSV is shed in saliva, nasal and rectal secretions, making it highly transmissible and difficult to control once introduced to a herd. Moreover, PRRSV is highly mutable and prone to recombination, resulting in increased genetic diversity. This variability contributes to inconsistent and often unpredictable vaccine effectiveness, making PRRS one of the most difficult diseases to control and prevent. More information:

• A Spanish Porcine Reproductive and Respiratory Syndrome Virus 1 Strain Is Highly Virulent in Pigs Under Experimental Conditions